This paper reviews the production technologies for sourcing lecithins from the oil-bearing seeds soybean, rapeseed and sunflower kernel. The phospholipid composition is measured by newly developed HPLC-LSD and 31 P-NMR methods. The phospholipid compositions of the three types of lecithin show small differences, while the fatty acid composition is largely equivalent to the oil source. Regulatory specifications (FAO/WHO, EU, FCC) and DGF and AOCS analytical methods for product quality are compiled. Phospholipid modifications by enzymatic hydrolysis, solvent fractionation, acetylating and hydroxylation processes result in lecithins with specific enhanced hydrophilicity and oil-in-water emulsifying properties. New available phospholipase and lipase enzymes represent opportunities for the esterification of phospholipids with special omega fatty acids and serine groups. Application characteristics are given for use in yellow fat spreads, baked goods, chocolate, agglomerated instant powders, liposome encapsulation, animal feed, food supplements and pharmaceutics.

The surface activity and ultimately the performance of commercial lecithin can be improved by physical, chemical or enzymatic methods. These methods are reviewed along with a brief survey of the use of special lecithins in certain food and non-food applicatlons. Emphasis is placed on margarine, instant foods, leather fatting and mosquito control systems.

No abstract

Soy lecithins are important emulsifiers used in the food, feed, pharmaceutical, and technical industries. Native lecithin is derived from soybean oil in four steps: hydration of phosphatides, separation of the sludge, drying, and cooling. Such lecithin has both W/O and O/W emulsifying properties. Products with improved emulsifying properties can be obtained by modifications, involving mainly fractionation in alcohol, hydrolysis (enzymatic, acid, or alkali), acetylation, or hydroxylation. Careful processing is required to produce lecithins of a high chemical, physical, and bacteriological quality.

Food consists of three components, carbohydrates, proteins and fats, which are linked by various types of chemical and physical bonds. The interactions at the interface of dispersions and emulsions are influenced by surface‐active emulsifiers such as lecithins. Synergistic effects on the emulsion stability can be obtained by selected protein‐lecithin combinations. Hydrocolloids enhance the stability by viscosity increase and gel formation. Lecithins are modified physically and enzymatically, giving a range of food grade emulsifiers with different hydrophilic‐lipophilic‐balance (HLB) values. The influence of phospholipid fractions in the homogenization process can be measured by the particle size distribution technique (PSD) and emulsifying tests, which assess the emulsion stability. Basic studies on the interactions of surface‐active proteins and lecithins in emulsions are reviewed. The principles of combined use of proteins and lecithins are presented for processed foods such as mayonnaise, margarine, instant milk powders, fat reduced cookies, and chocolate coatings for ice cream dipping. A new challenge for the food industry is the liposome encapsulation technique. Liposomes are produced with phosphatidylcholine fractions to encapsulate water and oil soluble components, such as flavours, in one capsule.